Method of producing a coreless armature

ABSTRACT

A coreless armature and a method for producing the same, characterized in that, on the outer surface of an annular body, a plurality of teeth-like projections are provided with equal spacing therebetween and in a manner extending along the generatrices of the annular body from a base part thereof, effective parts of armature coils are inserted evenly in the slots formed between the teeth-like projections, and the entire assembly is thereafter impregnated with a synthetic resin for solidifying the assembly into an integral body. The base part of the annular body from which the plurality of teeth-like projections project may be removed thereafter from the thus solidified armature assembly.

United States Patent 1 [111 3,740,836 Kumada et a1. 14 1 June 26, 1973 [5 METHOD OF PRODUCING A CORELESS 3,290,528 12/1966 Adler et al 310/266 MATURE FOREIGN PATENTS on APPLICATIONS [75] Inventors: ShojiKumlda; Taduhi T h. 635,624 4/1950 Great Britain 310/2 6 both of lruma, Japan 73 Assign; Kabuki t Primary Examiner-Charles W. Lanham s i Fukuokihken Japan Assistant ExaminerCarl E. Hall An -J h Th C 11 221 Filed: Sept. 28, 1971 mm o n was e a [21] Appl. No.: 184,473 [57]. ABSTRACT v A coreless armature and a method for producing the [30] Foreign Application Priority D g. same, characterized in that, on the outer surface of an Sept. 28 1970 11.31,. 45185678 3 plu'ality leeth'like Pmiecim v provided with equal spacing therebetween and in a 52 us. (:1 29/598, 29/605 310/266 mannflPxtending Benemric" the annular 511 111:. CI. .1 11021 15/02, 11621: 15/10 a base Pilrt there, effective Parts 58 Field 61 Search 29/598 596 605- 115 are insened evenly'in 6 tween the teeth-like projections, and the entire assembly is thereafter impregnated with a synthetic resin for 56] References cued solidifying the assembly into an integral body. The base part of the annular body from which the plurality of UNITED STATES PATENTS teeth-like projections project may be removed thereaf- 3,538,364 11/1970 Favereau 310/266 X er from the thus sohdified armature assembly 3,488,837 1/1970 Massouda 310/266 X 3,675,102 7/1972 SidoI-ov et a1 310/266 1 Claim, 3 Drawing Figures 7 Q 3 l 1, 1 I p L w PAIENTEUJIJN 26 I973 FIG.

FIG.2

METHOD OF PRODUCING-A CORE-LESS ARMATURE BACKGROUND-F THE INVENTION This invention relatesgenerallyto armatureshaving no iron cores; and more particularly toan improvement thereof wherein structural unbalance as well as magnetic unbalance arev substantially eliminated'aTlie' invention also relates to an improved method for producing the coreles's armature of the above described features.

'III ECOI'IU'OlSySIeI'II such astha'tfor a peripheral apparatus for electronic computers'o'r' a numerically. con trolled machine tool, wherein'preeision' control is particularly essential, a tachometer generator ofhighlyac= curate operational characteristics is required;-and"one of the fundamental requirements for the tachometer generator is that no ripple lie-included in the induced voltage. A reason for the inclusion of ripples in the induced voltage ofthe conventional tach'ometergene'ra tor is the difficulty of eliminatingstructural or'magnetic unbalance in the arm'atu're winding. Although the influ-- ence of the magnetic unbalance canbe substantially eliminated by a coreless construction of the armature (orby the-moving coilt'ype armature);.such a-construu tion of the armaturehas been-found toha-ve a'tendency to cause far greater unbalance in the distribution. of

coils than the ordinary arrnaturewherein c'oils are dis? tributed in the core-slots.

Another requirement for" the tachometer generator applied in the abovementioned technieal fields isthatt the momentum of the armature be substantially minimized so that instantaneous variation of the measurement can be detected with fidelity.

SUMMARY OF THE INVENTION Therefore, a primary object of the present invention is to provide an improved armature having no iron core, wherein all of the above deserib'e'd dr'awb'a'cks of the conventional apparatus can be substantiallyeliminated. r

Another object of the'p'resent invention" is to provide an improved armature of, forinstance, a tachometer generator which is simple" in construction and easyto manufacture.

Still-another object of the present inv'ention is toprovide an improved armature of, for instance, atacho'mete'r generator, the moment" of inertia of'which can-be substantially. minimized.

A further objectof thepresentinvention-is to provide an improved armature of corel'ess' type, wherein the: above mentioned distributional unbalance aswell as the magnetic unbalance can be substantially eliminated.

An additional object of the present invention is to provide an improved method for producing the coreless armature wherein allof the-above-described advantageous features are preserved".

These and other objects-of theprese'nt invention" canbe' achieved by an armature of core'lesstype and a method for producing the same, wherein on the outer surface of an annular body, a plurality of teeth-like projections are provided with equal spacing therebetween and in a manner extending alongthe generatrices-of the annular body, effective partsof armature coilsare inserted evenly in the slots formed between the teeth-like projections, and the entire assembly is thereafter im-" pregnated with a synthetic resin for solidifying the assembly'into' an integral body. In one aspect, the base portion of the annular body fromwh'ich the plurality of teeth-like projections project is removed thereafter frorn' th'e'thus solidified armature assembly.

The nature, principle, and utility of the present inventionwill-be better understood from the following detailed description of the invention when read in conjuncti'onwith the accompanying drawing, in which like parts are designatedby like reference numerals.

BRIEF DESCRIPTION OF DRAWING In the drawings:

FIG. 1 is a longitudinal sectional view of the upper halfof'a dlc. apparatus wherein an armature according to'the present invention is employed;

FIG. 2' is afragmental sectional view of an armature constituting an embodiment'of the present invention; and

FIG; 3 isa view'similar. to FIG. 2 of an armature constitutinganother embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Referring now to FIG. 1, there is indicated therein a die. machine orapparatus employing the coreless armature according to the present invention. The apparatus or machine comprises amachine frame 1, an annular permanent magnet 2 including field poles, a yoke 3 formed in a part of the machine frame 1 to oppositely 1 The armature comprises an annular body 9 made of a synthetic resin" and having projections 10 of twice the number of the armature coils extending radially outwardl'y of the annular body 9 with equal spacing therebetweenand having a height equal'to that of the effective part of the armature coil.'Between each pair of the two-adjacentprojections 10, an effective part 11 of the armature coils is interposed, and, when it is required, a-bind wire of, for. instance, glass tape is wound around the outer surface of the armature 4. The armature thus assembled is thereafter impregnated with a synthetic 9'of thev armature thus solidified is removed by machin-.

ingor by merely'pulling out. In the latter case, the base part and the teeth-like projections 10 of the annular body 9'are made easily separable beforehand. Preferably the base part of the annular body 9 is divided into two'or three pieces. The armature of thisembodiment is apparently of a lowerinertia than that of the previous embodiment.

Although in the above description, the number of the teeth-like projections has been selected to be twice the number of coils, this number may be equal to the number of coils as in the case of as ordinary armature or may be more than the number of coils so that the coil l. A method for producing a coreless armature comprising the steps of providing on the outer surface of an annular body of insulating material a plurality of teethlike projections equally spaced apart from each other and extending in'the direction of the axis of the annular body from abase part thereof, inserting effective parts of armature coils evenly in the slots formed between the teeth-like projections, impregnating the entire assembly with a synthetic resin for solidifying theassembly into an integral body, thereafter removing said-base part of the annular body from the solidified armature assembly. 

